This application is related to and claims priority from Japanese Patent Applications No. Hei. 9-340961 filed on Dec. 11, 1997, No. Hei. 9-341135 filed on Dec. 11, 1997, No. Hei. 9-341159 filed on Dec. 11, 1997, No. Hei. 10-16706 filed on Jan. 29, 1998, and No. Hei 10-50764 filed on Mar. 3, 1998, the contents of which are hereby incorporated by reference.
1. Field of the Invention:
The present invention relates to a cooling device having a boiling unit in which refrigerant is boiled and evaporated, and a condensing unit in which refrigerant is condensed and liquefied.
2. Description of Related Art:
In a conventional heat exchanger described in JP-A-56-119492, a boiling unit and a condensing unit are connected circularly using two connection pipes. Therefore, refrigerant boiled in the boiling unit flows into the condensing unit through one connection pipe, is liquefied in the condensing unit, and is returned to the boiling unit through the other connection pipe. However, as shown in FIG. 31, gas refrigerant is ununiformly distributed in the condensing unit. That is, gas refrigerant mainly flows into a refrigerant passage xe2x80x9caxe2x80x9d proximate to an gas-refrigerant inlet side, and hardly flows into a refrigerant passage xe2x80x9cbxe2x80x9d far from the gas-refrigerant inlet side. Thus, all the condensing unit cannot be effectively used, and heat-radiating performance of refrigerant in the condensing unit is decreased. Further, when the connection pipes are made longer or are bent, pressure loss in the refrigerant passage becomes larger, and a surface of liquid refrigerant rises in the condensing unit. Therefore, condensed liquid refrigerant stays in a refrigerant passage xe2x80x9ccxe2x80x9d where gas refrigerant hardly flows. Thus, the heat-radiating performance of refrigerant is further decreased in the condensing unit.
On the other hand, when a part of condensed liquid refrigerant is evaporated or a part of gas refrigerant is condensed in the connection pipes of the cooling device, convection flow of refrigerant is generated in the connection pipes, and the circulation of refrigerant in the cooling device is impeded. Therefore, the arrangement of the connection pipes is restricted.
In view of the foregoing problems, it is a first object of the present invention to provide a cooling device having first and second heat exchangers, in which gas refrigerant flowing into the second heat exchanger is diffused so that heat-radiating performance of gas refrigerant is improved in the second heat exchanger.
It is a second object of the present invention to provide a cooling device in which a connection pipe for connecting first and second heat exchangers can be freely arranged while circulation performance of refrigerant is improved.
It is a third object of the present invention to provide a cooling device in which a connection pipe for connecting first and second heat exchangers is formed to prevent gas refrigerant from being liquefied or liquid refrigerant from being evaporated in the connection pipe.
It is a fourth object of the present invention to provide a cooling device in which reserve refrigerant is stored in a connection pipe for connecting first and second heat exchangers so that cooling performance is maintained even when refrigerant leaks from the cooling device.
It is a sixth object of the present invention to provide a cooling device in which both first and second heat exchangers are connected using a short and straight connection pipe.
According to a first aspect of the present invention, in a cooling device including a first heat exchanger in which refrigerant is boiled and a second heat exchanger in which refrigerant condensed, there is provided with a diffusion unit which diffuses gas refrigerant flowing into an upper tank of the second heat exchanger to all the upper tank. Therefore. it can prevent gas refrigerant from mainly flowing into an inlet side in the upper tank of the second heat exchanger, and gas refrigerant can uniformly flows in the second heat exchanger. Thus, an entire area of the second heat exchanger can be effectively used for condensing gas refrigerant, and heat-radiating performance of refrigerant in the second heat exchanger can be improved.
Preferably, the diffusion unit is a diffusion plate having a plurality of openings each of which has opening area smaller than a passage sectional area of a first connection pipe through which gas refrigerant from the first heat exchanger is introduced into the upper tank of the second heat exchanger. Therefore, an inner space of the upper tank of the second heat exchanger can be divided into upper and lower spaces. Thus, gas refrigerant introduced into the upper tank of the second heat exchanger is diffused in all the upper tank while passing through the openings of the diffusion plate. As a result, the heat-radiating performance of refrigerant in the second heat exchanger can be further improved.
Further, the first connection pipe has a plurality of branched pipes connected to the upper tank of the second heat exchanger so that gas refrigerant is introduced into the upper tank of the second heat exchanger from the branched pipes. Therefore, gas refrigerant can be uniformly introduced into the upper tank of the second heat exchanger through the branched pipes, and can be readily diffused in the upper tank.
Preferably, at least one of the first connection pipe and a second connection pipe through which liquid refrigerant is introduced from a lower tank of the second heat exchanger to the first heat exchanger is formed into a multi-pipe structure in which a plurality of pipes having different diameters are assembled approximately concentrically. In the plurality of concentric pipes of the connection pipe, heat outside the most outer pipe is hardly transmitted into refrigerant flowing through an inner pipe. Thus, it can prevent gas refrigerant from being condensed or liquid refrigerant from being evaporated in the connection pipe having the multi-pipe structure, and circulation performance of refrigerant can be improved. As a result, the connection pipe can be readily arranged in the cooling device.
More preferably, the connection pipe has a predetermined pipe length so that a predetermined reserve refrigerant is stored, the second connection pipe has a lateral pipe portion extending approximately horizontally, and the lateral pipe portion is disposed between the first heat exchanger and the second heat exchanger. Therefore, cooling performance of the cooling device is maintained in a long time even when refrigerant leaks from the cooling device while a size of the cooling device is decreased.
According to a second aspect of the present invention, a cooling device includes a first heat exchanger in which liquid refrigerant is boiled and evaporated, and a second heat exchanger in which gas refrigerant is condensed and liquefied. In the cooling device, a part of tubes of the first and second heat exchangers is used as a refrigerant passage for circulating refrigerant between the first and second heat exchangers. Therefore, both the first and second heat exchangers can be connected using a short and straight connection pipe. Thus, strength of the connection pipe is improved, and assembling performance of the connection pipe to the first and second heat exchangers can be improved. Further, because the connection pipe is made shortly and straightly, the connection pipe can be produced in low cost.